package lhc.alg.top100;

/**
 * description: https://leetcode.cn/problems/sum-lists-lcci/
 *  这不就是两数相加
 * author: hongchen.liao
 * date:  2022/9/3
 */
public class _InterviewTopic_0205 {


    //Definition for singly-linked list.
    public class ListNode {
        int val;
        ListNode next;
        ListNode(int x) { val = x; }
    }

    class Solution {
        public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
            ListNode head = null, tail = null;
            int carry = 0;
            while(l1 != null || l2 != null){
                int n1 = l1 != null ? l1.val : 0;
                int n2 = l2 != null ? l2.val : 0;
                int sum = n1 + n2 + carry;
                if(head == null){
                    head = tail = new ListNode(sum % 10);
                }else{
                    tail.next = new ListNode(sum % 10);
                    tail = tail.next;
                }
                carry = sum / 10;
                if(l1 != null){
                    l1 = l1.next;
                }
                if(l2 != null){
                    l2 = l2.next;
                }
            }
            if(carry > 0){
                tail.next = new ListNode(carry);
            }
            return head;
        }
    }

}
